* A misspelling of a real name: There are many names that could be similar to "Dysert" like "Dyer", "Dygert", "Desart", etc.
* A fictional name: If it's from a book, movie, or game, then it's a fictional name and doesn't have a nationality.
* A surname: It might be a last name, in which case the person's nationality would depend on where their ancestors originated.
Please provide more context to determine the nationality.